This is the best line according to theory. If white can find a surprising resource here then his chances for equality are good. Currently,
there is no refutation in the lines above, so the jury is still out on this one!
It has come to my attention that after 5.d4 Nc6 6.d5 Ne5 7.f4 Ng6 8.e5 Ng8 9.d6?! cxd6 10.exd6 Qf6 11.Nb5 Nxf4! 12.Nc7+ Kd8 13.Qf3 Qe5+ is winning. Since I was unable to find an improvement please note that white should still have compensation if he deviates early on with something like 9.Qe2!? Bb4 10.f5!? Ne7 11.Bg5 which is still very dangerous.